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d7a131d3 | 1 | // SPDX-License-Identifier: GPL-2.0 |
e70a540b FG |
2 | /* |
3 | * STM32 Low-Power Timer PWM driver | |
4 | * | |
5 | * Copyright (C) STMicroelectronics 2017 | |
6 | * | |
7 | * Author: Gerald Baeza <gerald.baeza@st.com> | |
8 | * | |
e70a540b FG |
9 | * Inspired by Gerald Baeza's pwm-stm32 driver |
10 | */ | |
11 | ||
12 | #include <linux/bitfield.h> | |
13 | #include <linux/mfd/stm32-lptimer.h> | |
14 | #include <linux/module.h> | |
15 | #include <linux/of.h> | |
16 | #include <linux/platform_device.h> | |
17 | #include <linux/pwm.h> | |
18 | ||
19 | struct stm32_pwm_lp { | |
20 | struct pwm_chip chip; | |
21 | struct clk *clk; | |
22 | struct regmap *regmap; | |
23 | }; | |
24 | ||
25 | static inline struct stm32_pwm_lp *to_stm32_pwm_lp(struct pwm_chip *chip) | |
26 | { | |
27 | return container_of(chip, struct stm32_pwm_lp, chip); | |
28 | } | |
29 | ||
30 | /* STM32 Low-Power Timer is preceded by a configurable power-of-2 prescaler */ | |
31 | #define STM32_LPTIM_MAX_PRESCALER 128 | |
32 | ||
33 | static int stm32_pwm_lp_apply(struct pwm_chip *chip, struct pwm_device *pwm, | |
34 | struct pwm_state *state) | |
35 | { | |
36 | struct stm32_pwm_lp *priv = to_stm32_pwm_lp(chip); | |
37 | unsigned long long prd, div, dty; | |
38 | struct pwm_state cstate; | |
39 | u32 val, mask, cfgr, presc = 0; | |
40 | bool reenable; | |
41 | int ret; | |
42 | ||
43 | pwm_get_state(pwm, &cstate); | |
44 | reenable = !cstate.enabled; | |
45 | ||
46 | if (!state->enabled) { | |
47 | if (cstate.enabled) { | |
48 | /* Disable LP timer */ | |
49 | ret = regmap_write(priv->regmap, STM32_LPTIM_CR, 0); | |
50 | if (ret) | |
51 | return ret; | |
52 | /* disable clock to PWM counter */ | |
53 | clk_disable(priv->clk); | |
54 | } | |
55 | return 0; | |
56 | } | |
57 | ||
58 | /* Calculate the period and prescaler value */ | |
59 | div = (unsigned long long)clk_get_rate(priv->clk) * state->period; | |
60 | do_div(div, NSEC_PER_SEC); | |
61 | prd = div; | |
62 | while (div > STM32_LPTIM_MAX_ARR) { | |
63 | presc++; | |
64 | if ((1 << presc) > STM32_LPTIM_MAX_PRESCALER) { | |
65 | dev_err(priv->chip.dev, "max prescaler exceeded\n"); | |
66 | return -EINVAL; | |
67 | } | |
68 | div = prd >> presc; | |
69 | } | |
70 | prd = div; | |
71 | ||
72 | /* Calculate the duty cycle */ | |
73 | dty = prd * state->duty_cycle; | |
74 | do_div(dty, state->period); | |
75 | ||
76 | if (!cstate.enabled) { | |
77 | /* enable clock to drive PWM counter */ | |
78 | ret = clk_enable(priv->clk); | |
79 | if (ret) | |
80 | return ret; | |
81 | } | |
82 | ||
83 | ret = regmap_read(priv->regmap, STM32_LPTIM_CFGR, &cfgr); | |
84 | if (ret) | |
85 | goto err; | |
86 | ||
87 | if ((FIELD_GET(STM32_LPTIM_PRESC, cfgr) != presc) || | |
88 | (FIELD_GET(STM32_LPTIM_WAVPOL, cfgr) != state->polarity)) { | |
89 | val = FIELD_PREP(STM32_LPTIM_PRESC, presc); | |
90 | val |= FIELD_PREP(STM32_LPTIM_WAVPOL, state->polarity); | |
91 | mask = STM32_LPTIM_PRESC | STM32_LPTIM_WAVPOL; | |
92 | ||
93 | /* Must disable LP timer to modify CFGR */ | |
94 | reenable = true; | |
95 | ret = regmap_write(priv->regmap, STM32_LPTIM_CR, 0); | |
96 | if (ret) | |
97 | goto err; | |
98 | ||
99 | ret = regmap_update_bits(priv->regmap, STM32_LPTIM_CFGR, mask, | |
100 | val); | |
101 | if (ret) | |
102 | goto err; | |
103 | } | |
104 | ||
105 | if (reenable) { | |
106 | /* Must (re)enable LP timer to modify CMP & ARR */ | |
107 | ret = regmap_write(priv->regmap, STM32_LPTIM_CR, | |
108 | STM32_LPTIM_ENABLE); | |
109 | if (ret) | |
110 | goto err; | |
111 | } | |
112 | ||
113 | ret = regmap_write(priv->regmap, STM32_LPTIM_ARR, prd - 1); | |
114 | if (ret) | |
115 | goto err; | |
116 | ||
117 | ret = regmap_write(priv->regmap, STM32_LPTIM_CMP, prd - (1 + dty)); | |
118 | if (ret) | |
119 | goto err; | |
120 | ||
121 | /* ensure CMP & ARR registers are properly written */ | |
122 | ret = regmap_read_poll_timeout(priv->regmap, STM32_LPTIM_ISR, val, | |
123 | (val & STM32_LPTIM_CMPOK_ARROK), | |
124 | 100, 1000); | |
125 | if (ret) { | |
126 | dev_err(priv->chip.dev, "ARR/CMP registers write issue\n"); | |
127 | goto err; | |
128 | } | |
129 | ret = regmap_write(priv->regmap, STM32_LPTIM_ICR, | |
130 | STM32_LPTIM_CMPOKCF_ARROKCF); | |
131 | if (ret) | |
132 | goto err; | |
133 | ||
134 | if (reenable) { | |
135 | /* Start LP timer in continuous mode */ | |
136 | ret = regmap_update_bits(priv->regmap, STM32_LPTIM_CR, | |
137 | STM32_LPTIM_CNTSTRT, | |
138 | STM32_LPTIM_CNTSTRT); | |
139 | if (ret) { | |
140 | regmap_write(priv->regmap, STM32_LPTIM_CR, 0); | |
141 | goto err; | |
142 | } | |
143 | } | |
144 | ||
145 | return 0; | |
146 | err: | |
147 | if (!cstate.enabled) | |
148 | clk_disable(priv->clk); | |
149 | ||
150 | return ret; | |
151 | } | |
152 | ||
153 | static void stm32_pwm_lp_get_state(struct pwm_chip *chip, | |
154 | struct pwm_device *pwm, | |
155 | struct pwm_state *state) | |
156 | { | |
157 | struct stm32_pwm_lp *priv = to_stm32_pwm_lp(chip); | |
158 | unsigned long rate = clk_get_rate(priv->clk); | |
159 | u32 val, presc, prd; | |
160 | u64 tmp; | |
161 | ||
162 | regmap_read(priv->regmap, STM32_LPTIM_CR, &val); | |
163 | state->enabled = !!FIELD_GET(STM32_LPTIM_ENABLE, val); | |
164 | /* Keep PWM counter clock refcount in sync with PWM initial state */ | |
165 | if (state->enabled) | |
166 | clk_enable(priv->clk); | |
167 | ||
168 | regmap_read(priv->regmap, STM32_LPTIM_CFGR, &val); | |
169 | presc = FIELD_GET(STM32_LPTIM_PRESC, val); | |
170 | state->polarity = FIELD_GET(STM32_LPTIM_WAVPOL, val); | |
171 | ||
172 | regmap_read(priv->regmap, STM32_LPTIM_ARR, &prd); | |
173 | tmp = prd + 1; | |
174 | tmp = (tmp << presc) * NSEC_PER_SEC; | |
175 | state->period = DIV_ROUND_CLOSEST_ULL(tmp, rate); | |
176 | ||
177 | regmap_read(priv->regmap, STM32_LPTIM_CMP, &val); | |
178 | tmp = prd - val; | |
179 | tmp = (tmp << presc) * NSEC_PER_SEC; | |
180 | state->duty_cycle = DIV_ROUND_CLOSEST_ULL(tmp, rate); | |
181 | } | |
182 | ||
183 | static const struct pwm_ops stm32_pwm_lp_ops = { | |
184 | .owner = THIS_MODULE, | |
185 | .apply = stm32_pwm_lp_apply, | |
186 | .get_state = stm32_pwm_lp_get_state, | |
187 | }; | |
188 | ||
189 | static int stm32_pwm_lp_probe(struct platform_device *pdev) | |
190 | { | |
191 | struct stm32_lptimer *ddata = dev_get_drvdata(pdev->dev.parent); | |
192 | struct stm32_pwm_lp *priv; | |
193 | int ret; | |
194 | ||
195 | priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL); | |
196 | if (!priv) | |
197 | return -ENOMEM; | |
198 | ||
199 | priv->regmap = ddata->regmap; | |
200 | priv->clk = ddata->clk; | |
201 | priv->chip.base = -1; | |
202 | priv->chip.dev = &pdev->dev; | |
203 | priv->chip.ops = &stm32_pwm_lp_ops; | |
204 | priv->chip.npwm = 1; | |
f6ea025f GB |
205 | priv->chip.of_xlate = of_pwm_xlate_with_flags; |
206 | priv->chip.of_pwm_n_cells = 3; | |
e70a540b FG |
207 | |
208 | ret = pwmchip_add(&priv->chip); | |
209 | if (ret < 0) | |
210 | return ret; | |
211 | ||
212 | platform_set_drvdata(pdev, priv); | |
213 | ||
214 | return 0; | |
215 | } | |
216 | ||
217 | static int stm32_pwm_lp_remove(struct platform_device *pdev) | |
218 | { | |
219 | struct stm32_pwm_lp *priv = platform_get_drvdata(pdev); | |
e70a540b | 220 | |
2c2059c0 | 221 | pwm_disable(&priv->chip.pwms[0]); |
e70a540b FG |
222 | |
223 | return pwmchip_remove(&priv->chip); | |
224 | } | |
225 | ||
226 | static const struct of_device_id stm32_pwm_lp_of_match[] = { | |
227 | { .compatible = "st,stm32-pwm-lp", }, | |
228 | {}, | |
229 | }; | |
230 | MODULE_DEVICE_TABLE(of, stm32_pwm_lp_of_match); | |
231 | ||
232 | static struct platform_driver stm32_pwm_lp_driver = { | |
233 | .probe = stm32_pwm_lp_probe, | |
234 | .remove = stm32_pwm_lp_remove, | |
235 | .driver = { | |
236 | .name = "stm32-pwm-lp", | |
237 | .of_match_table = of_match_ptr(stm32_pwm_lp_of_match), | |
238 | }, | |
239 | }; | |
240 | module_platform_driver(stm32_pwm_lp_driver); | |
241 | ||
242 | MODULE_ALIAS("platform:stm32-pwm-lp"); | |
243 | MODULE_DESCRIPTION("STMicroelectronics STM32 PWM LP driver"); | |
244 | MODULE_LICENSE("GPL v2"); |